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COVID-19 vaccine in patients with CLL
Figure 4. A simple scoring model to predict response to the BNT162b2 mRNA COVID-19 vaccine in individual patients with chronic lymphocytic leukemia. IgM, IgA and IgM levels in mg/dL; Hgb: hemoglobin.
elicit robust CD4+ and CD8+ T-cell responses.23 More data regarding the role of cellular responses in patients with CLL are still awaited in order to establish whether this system provides additional protection or whether the T- cell anergy known to occur in these patients also affects this particular arm of the immune response. However, based on our understanding of immunity to virus vaccina- tions, T-cell immunity has a major role in generating durable immunity. In addition, as detailed in the varicel- la-zoster vaccine study referenced above,12 CLL patients can generate potentially effective antigen-specific CD4+ T-cell responses to vaccines even when on treatment with BTK inhibitors.
In principle, it seems to be important to be able to pre- dict the response to vaccination in patients with CLL and because of this we have formulated an original, simple, seven-parameter score which can be readily applied worldwide. It should, however, be taken into considera- tion that we based our model on in vitro markers of humoral immunity that do not necessarily predict clinical benefit and it should, therefore, be used with caution.
Our study has several limitations: Firstly, we used three different assays to measure immune response in our cohort of patients and differences between these com- mercial kits and their reference ranges must be taken into consideration. On the other hand, the results obtained appear to reflect the true "real-world" situation accurate- ly, in which several different kits are being used world- wide with all achieving similar results. Indeed, a study comparing the sensitivity of the various serological assays has already been published indicating a sensitivity of 84.7%, 82.4% and 89.4% for the Abbott, DiaSorin and ELISA kits, respectively.17,18 Other research has also shown strong agreement between the results of different kits.16 A second limitation of our study is that it lacks data regarding possible past exposure or asymptomatic illness to SARS-CoV-2 itself. because the “local policy“ was to
vaccinate only the "non-infected/recovering from COVID-19 infection" population. We feel that this deci- sion could possibly have affected our results but only in a very limited manner.
In conclusion, the results of this study showed that the humoral immune response to the BNT162b2 mRNA COVID-19 vaccine is impaired in patients with CLL. We were able to generate a simple seven-parameter score which helps to predict individual immune responses. Further studies are still required to define the exact role of the cellular immune response and the possible effect of a third dose of the vaccine in these patients.
In the long run it is our responsibility as a society to ensure that a high percentage of the healthy population is vaccinated so that we can protect more vulnerable indi- viduals with underlying disorders such as CLL who are only partially capable of mounting an effective immune response following vaccination.
Disclosures
No conflicts of interest to disclose.
Contributions
TT and OB designed, organized and wrote the manuscript. LR performed the statistical and machine learning analysis including the seven-parameter models, and was involved in writing the man- uscript. APol helped to write the manuscript. GI, AB, LS, NG, SS, ND, AA, GRYL, SSBD, RF, APaz, and IL contributed patients’ data.
Acknowledgments
We thank the study coordinators, with special thanks to Mrs. AndreaShoukair.
Funding
This study was supported by a grant from Janssen Pharmaceutical, number EV00261620.
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